The Bulgarian news agency Sofia reported that the bomber was carrying an American passport and Michigan driver’s license. Both documents are believed to be forgeries.

Sofia also reported that the Bulgarian Interior Ministry has managed to recover the fingerprints of the bomber, which they have submitted to the FBI in the United States and the international police organization Interpol. The FBI and CIA have joined Israeli and Bulgarian officials in investigating the attack.

Interior Minister Tsvetan Tsvetanov told Sofia that DNA tests would be run to determine the identity of the Caucasian man, who the minister described as casually dressed with nothing suspicious about his appearance to set him apart from the crowd of people at the airport.

The ministry did not indicate how the police came to the conclusion that the man was the suicide bomber.

The video released by the police on Thursday shows a young man with long hair wearing a hat and backpack, dressed in a blue T-shirt and Bermuda shorts. He was filmed by the video camera approximately one hour before the attack took place.

Bulgarian Prime Minister Boyko Borisov said Thursday the attack was likely carried out by a suicide bomber who detonated as he boarded the bus. Initially, investigators believed the bomb had been set off from within a suitcase on the bus.

The latest death toll in the bus bombing was put at six — five Israelis, one of whom died overnight in the hospital, and the Bulgarian bus driver.

Three victims remained in serious condition at a hospital in the capital of Sofia. The rest of the 33 wounded were in a local hospital or still at the airport in Burgas waiting to be flown home by Israeli rescue teams.

The rescue teams said the wounded would arrive in Israel around noon. Five planes were flying Israeli tourists home, including some who wanted to cut their visit short.